Internal combustion engine



Jan. 30, 1940. J. J. MCCARTHY 2,188,368

INTERNAL COMBUSTION ENGINE Filed Jan. 3, 1939 Inuni'or: 3 Mgmw I fliiotneys.

Patented Jan. 30, 1940 UNITED STATES PATENT OFFICE Application January 19 Claims.

This invention relates to internal combustion engines and more particularly to an engine of the opposed-piston-type,

It is a common complaint that the head of a 6 piston, which covers and uncovers the exhaust ports in a cylinder of an opposed-piston-type engine, becomes excessively heated.

It is, therefore, the primary aim and object of the present invention to make provisions for 10 cooling the head of the exhaust-controlling piston in an opposed-piston-type engine.

According to the present invention, this primary object is accomplished by mounting an exhaust valve of the poppet-type in the head of a piston which reciprocates in a ported cylinder and has a sleeve-like extension in which the opposed piston reciprocates, both pistons being directly connected by connecting rods with one crank shaft. The exhaust valve is normally spring-retained on its seat in the head of the first mentioned piston, hereafter called sleevepiston, and opens into the chamber formed by the two pistons, hereafter called piston chamber, in order to provide communication between the latter and a ported exhaust chamber which is provided in the head of said sleeve-piston. The ports of said exhaust chamber communicate during a preassigned portion of each cycle of the sleeve-piston with exhaust ports in the cylinder wall for the discharge of the products of combustion from said piston chamber. The stem of the exhaust valve extends through and beyond the exhaust chamber of the sleeve-piston and is effectively cooled by air under at- 86 mospheric conditions in a manner to be described in detail in the following specification. A stop is provided which is engaged by the valve stem before the sleeve-piston reaches its outer dead center position, causing the valve to be' opened for the discharge of the products of combustion from the piston cha'rnber into the exhaust chamber of the sleeve piston and from there into the exhaust ports in the cylinder wall. The heat absorbed by the valve head is transmitted to the cooled valve stem so that the former never becomes unduly hot. The exhaust valve is made of highly heat-resistive material and its head is preferably of a large diameter so that it constitutes the greater part of the head area. of the sleeve-piston which is exposed to the piston chamber and exercises a satisfactory control over the temperature of the head of said sleeve piston.

It is another object of the present invention to provide for the recovery of a substantial por- 1939, Serial No. 249,011

tion of the heat absorbed by the valve-cooling air and its introduction into the combustible charge in the cylinder.

It is also among the objects of the present invention to provide for cushioning the impact I between the stem of the exhaust valve and its stop.

Before explaining in detail the present invention it is to be understood that the invention is not limited in its application to the details of 10 construction and arrangement of parts illustrated in the accompanying drawing, since the invention is capable of other embodiments and of being practiced or carried out in various ways.

Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation, and it is nt intended to limit the invention claimed hereinv beyond the requirements of the prior art.

In the drawing: 20

Fig. 1 is a fragmentary cross-section through a cylinder of an internal combustion engine, embodying the present invention.

Fig. 2 is a. greatly reduced section similar to Fig. 1, showing additional elements of the engine 25 which have been omitted in Fig. 1.

Referring to Fig. 1, the reference numeral I 0 designates a water-jacketed cylinder, having in its cylindrical wall spaced sets of intake and exhaust ports II and i2, respectively, which communicate with suitable intake and exhaust manifolds l3 and M, respectively. While only one cylinder is disclosed in the drawing, the engine may be provided with a plurality of cylinders cast in a block, for instance. Inasmuch as the present as invention is fully embodied in a single cylinder, however, only one cylinder will be described herein in detail.

Reciprocable in the cylinder I0 is a sleevepiston l5 having a head l6 and a sleeve-like skirt I1 which is provided with a plurality of intake ports 18 and one or more fuel ducts l9. Reciprocable within the sleeve piston I5 is the thereto opposed piston 20, both pistons l5 and 20 being connected by connecting rods 2i and 22, respectively, with the opposed cranks 23 and 24, respectively, of a crank shaft 25 (Fig. 2) which is suitably journalled in a crank case (not shown).

Within the head l6 of the sleeve piston I5 is formed an exhaust chamber 26, having ports 21 that provide communication between said exhaust chamber 26 and the exhaust ports, in the cylinder wall during a preassigned portion of each cycle of said sleeve-piston. The exhaust chamber 26 also communicates substantially duringthe same portion of each cycle of said sleeve-piston IS with the piston chamber 28, formed by and within both pistons, through an opening 29 between an inserted valve seat 30 in the piston head l6 and the head 3| of a poppet valve 32. The inserted valve seat 38 and the valve 32 are preferably made of highly heatresistive material, and said valve is guided for movement to and from its seat, 30 in a bushing 33 in the piston head IS. The valve 32 is normally urged into engagement with its seat 38 by a compression spring 34 which may be mounted in the self-explanatory manner shown in Fig. 1. 7

Mounted on top of the cylinder I is a cylinder head 35, having a centrally recessed boss 36 in which is fitted a sleeve 3'! wherein the stem 38 of the exhaust valve 32 is slidable. Screwed or otherwise longitudinally adjustably secured in a counterbore 39 of the boss 36 is a plug 48, providing a stop surface 4| which is adapted to be engaged, or substantially engaged as hereafter described, by the valve stem 38 during movement of the sleeve-piston l into its outer dead center position, shown in Fig. 1, in order to cause opening of the exhaust valve 32 substantially when the ports 21 in the exhaust chamber 26 of said piston |5 communicate with the exhaust ports l2 in the cylinder wall. The timing of the exhaust valve 32 may be varied to suit by longitudinally adjusting the plug 40"which provides the stop surface 4| for the valve stem 38. A nut 48a locks the plug 40 in longitudinally adjusted position.

The cylinder head 35 provides a chamber 42 which communicates with the atmosphere through suitable openings 43. Provided in a side wall of the cylinder head 35 is an air-discharge opening 44 which communicates through a conduit 46 with the low pressure side of any conventional supercharger 45 (Fig. 2) the high pressure side of which communicates with the intake manifold I3 through a conduit 41. Suitably mounted in the cylinder head 35 adjacent the airdischarge opening 44 thereof is a baffle plate 48 which permits only air from the lower part of the cylinder head chamber 42 to enter said opening 44. Hence, most of the atmospheric air in the cylinder head chamber 42 must first flow past and cool' the exposed portion 49 of the valve stem 38 to which the heat from the valve head 3| is transmitted, before said air is drawn into the discharge opening 44 and from there into the supercharger 45. In this way, a substantial portion of the heat absorbed by the valve head 3| is converted into usefulness by being introduced into the combustible charge in the cylinder as will be readily understood. The valve head 3| is preferably made large in diameter so that the heat in the head of the sleeve piston I5 is well controlled by the above-described valvecooling method. To further cool the piston head l6 and particularly its exhaust chamber 26, the same is also provided with a plurality of cooling ribs 58 which are exposed to the air in the cylin- I der head chamber 42.

Provisions are also made for cushioning the impact between the stem 38 of the exhaust valve 32 and the stop surface 4| of the plug 40 when the sleeve piston |5 moves into its outer dead center position. To this end, the sleeve 31 is made to serve as a dash pot in which the valve stem 38 acts like a plunger. The cylinder head 35 is provided with two ducts 6| and 62 which communicate through suitable connections 63 and 64 respectively, with conduits 65 and 66,

respectively, which in turn communicate with a source of any suitable fluid. A liquid that will not evaporate when subjected to the heat in the sleeve 31, such as certain types of oil, makes an excellent fluid for this purpose. The duct 6| communicates with the interior of the sleeve 31 through a peripheral groove 6'! and communicating ducts 68 and 69 in the plug 40. More particularly, the ducts 68 and 69 communicate with each other through a bore III which provides a seat H for a check valve 12 that is normally closed by a compression spring 13, bearing with one end against said check valve and with its other end against a set screw 14. The compression of the spring 13 may be adjusted by manipulating the set screw 14, the same being locked in adjusted position by a nut I5. This check valve 12 permits the flow of liquid in one direction only, i. e., from the interior of the sleeve 31 to the duct 6| as will be readily understood. The other duct 62 in the cylinder head 35 communicates with the interior of the sleeve 31 through a duct 16 of the latter when the sleevepiston I5 is in its inner dead center position shown in dot-and-dash lines in Fig. 1, in which position the stem 38 of the exhaust valve 32 clears said duct 16 as shown in dot-and-dash lines in the same figure.

When the pistons are working, a partial vacuum is created in the sleeve 31 everytime the valve 32 moves from the full-line position into the dot-and-dash line position in Fig. 1 during each inward stroke of the sleeve-piston i5. and a slight amount of liquid will be drawn into the sleeve 31 from the duct 16 when the valve stem 38 clears said duct. When the sleeve-piston l5 moves in the opposite direction, 1. e., into its outer dead center position, the then closed valve 32 will move with said piston until the end of its stem 38 is in close proximity with the stop surface 4| of the plug 48 and the liquid therebetween has no other escape than through the check valve 12. Depending on the adjusted compression of the spring 13, the check valve 12 will impede the escape of the trapped liquid from the sleeve 31 through the ducts in the plug and into the return or discharge duct 6| in the cylinder head, with the result that the valve is slowed down before its stem 38 engages the stop surface 4| without making any noise. By proper adjustment of the compression of the check-valve spring 13 and/or proper selection of the width of the duct 69 in the plug 48, for instance, it may be accomplished that the valve stem 38 never actually engages the stop surface 4| of said plug 40 during normal running of the engine.

The peripheral groove 61 in the plug 40 is made of considerable width so that said groove may communicate with the duct 6| in the cylinder head in any longitudinally adjusted position within certain limits of said plug. The piston I5 also preferably consists of a separate head I6 and a separate sleeve H which may be detachably joined in the manner shown in Fig. 1, thus permitting removal of the piston head l6 to grind the exhaust valve 32, for instance, without disconnecting the piston sleeve I! from the crankshaft and removing it from the cylinder. I

Mounted in the cylinder wall are two fuel injectors 88 through which fuel is, forced by a suitably operated fuel pump or pumps (not shown) into the combustion chamber 8| (see dot-anddash line position of pistons I5 and 20 in Fig.

1) through the then aligning fuel ducts I! in the sleeve-piston I5. I

' The head of the other piston 20 is in its outer dead center position emciently cooled by the intake air which enters the piston chamber 28 through the intake ports l8 in the sleeve piston l5 immediately above the head of piston 20.

I claim:

1. In an internal combustion engine, the combination of a cylinder open at both ends; two pistons in the cylinder operating in opposite directions therein, one piston being slidable on the cylinder wall and the other piston being slidable in said one piston, means for supplying a combustible mixture to the space between the heads of said pistons, a normally spring-closed poppet exhaust valve in the head of said one piston, the head of said valve being exposed to the interior of said one piston and liftable into the latter in the direction of the cylinder axis; a stationary stop adapted to be engaged by the stem of said valve-when said one piston moves into its outer dead center position, thereby lifting said valve, and means for circulating a cooling fluid other than said combustible mixture about said stem.

2. In an internal combustion engine, the combination of a cylinder open at both ends and having exhaust ports in its wall; two pistons in the cylinder operating in opposite directions therein, one piston being slidable on the cylinder wall and having in its head an exhaust chamber with ports communicating with those in the cylinder wall substantially when said one piston is in its outer dead center position, and the other piston being slidable in said one piston; a normally spring-closed poppet exhaust valve in the head of said one piston for providing communication between the interior of said one piston and said exhaust chamber, the head of said valve being exposed to the interior of said one piston and liftable into the latter in the direction of the cylinder axis and the valve stem extending through and beyond said exhaust chamber; and a stationary stop adapted to be engaged by the end of said valve stem when said one piston moves into its outer dead center position, thereby lifting said valve.

3. The combination in an internal combustion engine as set forth in claim 2, further comprising a casing on and open to one end of the cylinder and in which said stop is provided, and means for flowing cooling air through said casing.

4. The combination in an internal combustion engine as set forth in claim 2,'further comprising a casing on and open to one end of the cylinder, a plug in said casing providing said stop and being adjustable axially of the cylinder, and

, means for flowing cooling air through said casing.

5. The combination in an internal combustion engine as set forth in claim 2, furthercomprising a casing on and open to one end of the cylinder and in which said stop is provided, and means for flowing cooling air through said casing, the head of said one piston being provided with cooling ribs exposed to the interior of said casing.

6. The combination in aninternal combustion engine as set forth in claim 2,- further comprising a casing on and open to one end of the cylinder and in which said stop is provided, and means for flowing cooling air through said oasing so that the inflowing air passes along the 7. The combination in an internal combustion engine as set forth in claim 2, further comprising a casing on and open to one end'of the cylinder and in which said stop is provided, cooling ribs on the head of said one piston exposed to the interior of said casing, and means for flowing cooling air through said casing so that the inflowing air passes along the valve stem from its end toward the valve head and past said cooling ribs and then leaves said casing.

8. The combination in an internal combustion engine as set forth in claim 2, further comprising a casing on and open to one end of the cylinder and inwhich said stop is provided, a supercharger, means for conducting'atmospheric air through said casing to the low pressure side of said supercharger, and means for conducting the supercharged air into the chamber formed by the pistons substantially when the latter are farthest apart.

9. The combination in an internal combustion engine as set forth in claim 2, further comprising a casing on and open to one end of the cylinder and in which said stop is provided, cooling ribs on the head of said one piston exposed to the interior of said casing, a'supercharger, means for conducting atmospheric air through said casing and to the low pressure side of said supercharger, and means for conducting the supercharged air into the chamber formed by the pistons substantially when the latter are farthest apart.

10. In an internal combustion engine, the combination of a cylinder open at one end to the atmosphere and having exhaust ports in its wall; and two pistons in the cylinder operating in opposite directions therein, one piston being slidable on the cylinder wall and .having adjacent its head exhaust ports in. itsskirt communicating with those in the cylinder wall substantially when said one piston is in its outer dead center position, and cooling ribs on its head facing said one cylinder end and being exposed to the atmosphere thereat, and the other piston being slidable in the skirt of said one piston.

11. The combination in an internal combustion engine as set forth in claim 10, further comprising a casing on and open to said one end of the cylinder, and means for flowing atmospheric air through said casing.

12. The combination in an internal combustion engine as set forth in claim 10 further comprising a casing on and open to said one end of the cylinder, and means for flowing atmospheric air through said casing so that the inflowing air passes toward said cooling ribs and then leaves said casing.

13. The combination in an internal combustion engine as set forth in claim 10, further comprising a casing on and open to said oneend of the cylinder, a supercharger, means for conducting atmospheric air through said casing and to the low pressure side of said supercharger, and means for conducting the supercharged air into the chamber formed by the pistons substantially when the latter are farthest apart.

14. In an internal combustion engine, the combination of a cylinder; two pistons in the cylinder operating in opposite directions therein, one piston being slidable on the cylinder wall and the other piston being slidable in said one piston; a normally spring-closed poppet exhaust valv in the head of said one piston, said valve being liftable into the chamber formed by the pistons for the discharge of the products of combustion therefrom and the valve stem extending axially of the cylinder outside said chamber; a stationary stop adapted to 'be engaged by said valve stem when said one piston moves into its outer dead center position to lift said valve; and a dash pot on one end of the cylinder for cushioning the impact between said valve stem and stop.

15. The combination in an internal combustion engine as set forth in claim 14, in which said dash pot comprises an annular recess in which the valve stem slides plunger-like and the bottom of which constitutes said stop, a check valve in said bottom permitting fluid to flow therethrough from said recess only, and a duct in the annular recess wall communicating with a source of fluid and being uncovered by said stem during movement of said one piston into its inner dead center position.

16. The combination in an internal combustion engine as set forth in claim 14, in which said dash pot comprises an annular recess in which the valve stem slides plunger-like, a plug longitudinally adjustable in said recess and comprising said stop, a check valve in said plug permitting fluid to flow therethrough from said recess only, and a duct in the annular recess wall communicating with a source of fluid and being uncovered by said stem during movement of said one piston into its inner dead center position.

17. The combination in an internal combustion engine as set forth in claim 14, in which said dash pot comprises an annular recess in which the valve stem slides plunger-like, a plug longitudinally adjustable in said recess and comprising said stop, a spring-urged check valve in said plug permitting fluid to flow therethrough from said recess only, means for adjusting the force of said spring, and a duct in the annular recess wall communicating with a source of fluid and being uncovered by said stem during movement of said one piston into its inner dead center position.

18. In an internal combustion engine, the combination of a cylinder open at both ends: two pistons in the cylinder operating in opposite directions therein, one piston being slidable on the. cylinder wall and the other piston being slidable in said one piston; a normally springclosed popp t exhaust valve in the head of said one piston, the head of said valves being exposed to the interior of said one piston and liftable into the latter in the direction of the cylinder axis, a stationary'stop adapted to be engaged by the stem of said valve when said one piston moves into its outer dead center position. thereby lifting said valve, and means for maintaining a substantially constant circulation o atmospheric air about said stem.

19. In an internal combustion engine, the combination of a cylinder open at both ends and having exhaust ports in its wall; two pistons in the cylinder operating in opposite directions therein, one piston being slidable on the cylinder wall and having in its head an exhaust chamber with ports communicating with those in the cylinder wall substantially when said one piston is in its outer dead center position, and the other piston being slidable in said one piston, a normally spring-closed poppet exhaust valve in the head of said one piston for providing communication between the interior of said one piston and said exhaust chamber, the head of said valve being exposed to the interior of said one piston and lif-table into the latter in the direction of the cylinder'axis and the valve stem extending through and beyond said exhaust chamber, a stationary stop adapted to be engaged by the end of said valve stem when said one piston moves into its outer dead center position, thereby lifting said-valve, and means for circulating atmospheric air about said stem.

JOHN J. MCCARTHY. 

